All are correct w.r.t. BOD (Biochemical Oxygen Demand), except

Options

A. It refers to the amount of oxygen that would be consumed if all the organic matter in one liter of water were oxidised by bacteria
B. The BOD test is a measure of the organic matter present in the water
C. The greater the BOD of waste water, less is its polluting potential
D. Waste water is treated till BOD is reduced significantly

Answer

### Step-by-Step Solution:

1. **Understanding BOD**: BOD stands for Biochemical Oxygen Demand. It is a measure of the amount of oxygen that microorganisms will consume while decomposing organic matter in water.

2. **Analyzing the Options**:
- **Option 1**: "It refers to the amount of oxygen that would be consumed if all the organic matter in 1 litre of water were oxidized by the bacteria."
- This statement is correct as it accurately describes BOD.

- **Option 2**: "The BOD test is a measure of the organic matter present in the water."
- This statement is also correct because BOD indicates the amount of organic matter in the water.

- **Option 3**: "The greater the BOD of wastewater, less its polluting potential."
- This statement is incorrect. In fact, a greater BOD indicates a higher polluting potential because it means there is more organic matter that requires decomposition by microorganisms.

- **Option 4**: "Wastewater is treated till BOD is reduced significantly."
- This statement is correct as wastewater treatment aims to reduce the BOD to minimize pollution.

3. **Identifying the Incorrect Statement**:
- The only incorrect statement among the options is **Option 3**. It contradicts the fundamental concept of BOD, which states that a higher BOD correlates with a greater polluting potential.

### Final Answer:
The incorrect statement regarding BOD is **Option 3**: "The greater the BOD of wastewater, less its polluting potential."

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